Volumetric Non-Contrast Pulmonary Perfusion Using Arterial Spin Labeled Magnetic Resonance Imaging




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Arterial spin labeled (ASL) magnetic resonance imaging (MRI) is a rapidly growing area of research with significant clinical potential, primarily because it can provide non-invasive quantitative perfusion maps. A significant portion of ASL application have been in the brain and kidneys, though quantitative pulmonary perfusion would be beneficial in the management of chronic lung conditions. The work presented in this dissertation aims to develop non-contrast pulmonary perfusion imaging using ASL for volumetric coverage of the entire lungs. The established FAIR ASL technique is applied at 3T for improved SNR and the reproducibility of quantified perfusion is demonstrated. Further developments are made to reduce the sensitivity of FAIR perfusion imaging to respiratory motion and to reduce unwanted vascular signal. This enabled robust measurement of perfusion across the entire lung using multi-slice FAIR. PseudoContinuous ASL is investigated for use in the lungs to further improve SNR. Different labeling strategies are explored and the effects of cardiac phase on ASL-measured perfusion are examined. Next, the presented lung perfusion imaging techniques are applied in a clinical setting to better understand the cardiopulmonary flow patterns in pediatric patients with Fontan circulation. To extend these techniques for 3D perfusion mapping, a Cartesian Acquisition with Spiral PRofile Ordering (CASPR) is developed to make ASL measurements more robust to sources of noise and motion artifacts. CASPR is demonstrated for brain and kidney perfusion imaging where ASL has been well established. This view ordering improved SNR and enabled 3D coverage of the brain and kidneys in similar scan times to a 2D slice. Finally, for ASL to be adopted for clinical perfusion imaging, it must be established as an accurate and reproducible perfusion measurement technique. A quality-control perfusion phantom is developed and tested to validate ASL-measured perfusion. In summary, the presented work makes ASL more valuable for clinical non-contrast measurement of pulmonary perfusion.



Magnetic resonance imaging, Perfusion (Physiology), Lungs